title: Molecular recognition and substrate mimicry drive the electron-transfer process between MIA40 and ALR.
abstract: Oxidative protein folding in the mitochondrial intermembrane space requires the transfer of a disulfide bond from MIA40 to the substrate. During this process MIA40 is reduced and regenerated to a functional state through the interaction with the flavin-dependent sulfhydryl oxidase ALR. Here we present the mechanistic basis of ALR-MIA40 interaction at atomic resolution by biochemical and structural analyses of the mitochondrial ALR isoform and its covalent mixed disulfide intermediate with MIA40. This ALR isoform contains a folded FAD-binding domain at the C-terminus and an unstructured, flexible N-terminal domain, weakly and transiently interacting one with the other. A specific region of the N-terminal domain guides the interaction with the MIA40 substrate binding cleft (mimicking the interaction of the substrate itself), without being involved in the import of ALR. The hydrophobicity-driven binding of this region ensures precise protein-protein recognition needed for an efficient electron transfer process.
authors.affiliation: Magnetic Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, Sesto Fiorentino, 50019 Florence, Italy. banci@cerm.unifi.it
authors.forename: Lucia
authors.initials: L
authors.lastname: Banci
authors.forename: Ivano
authors.initials: I
authors.lastname: Bertini
authors.forename: Vito
authors.initials: V
authors.lastname: Calderone
authors.forename: Chiara
authors.initials: C
authors.lastname: Cefaro
authors.forename: Simone
authors.initials: S
authors.lastname: Ciofi-Baffoni
authors.forename: Angelo
authors.initials: A
authors.lastname: Gallo
authors.forename: Emmanouela
authors.initials: E
authors.lastname: Kallergi
authors.forename: Eirini
authors.initials: E
authors.lastname: Lionaki
authors.forename: Charalambos
authors.initials: C
authors.lastname: Pozidis
authors.forename: Kostas
authors.initials: K
authors.lastname: Tokatlidis
mesh_terms: D001665:Binding Sites; D003579:Cytochrome Reductases / Q000737:chemistry* / Q000378:metabolism; D004579:Electron Transport / Q000502:physiology; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D050862:Oxidoreductases Acting on Sulfur Group Donors; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity / Q000502:physiology
chemical_list: C507282:CHCHD4 protein, human; D007527:Isoenzymes; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D005182:Flavin-Adenine Dinucleotide; D003579:Cytochrome Reductases; C500897:GFER protein, human; D050862:Oxidoreductases Acting on Sulfur Group Donors